Recursive chown That succesfully changed the ownership of the "dot" files, but had an unexpected (to him) side effect: /usr was also changed. Of course that would be true, because ".*" includes ".." and the ".." of /usr/fred is /usr. A useful command flag seemed to be difficult or impossible to use as desired.

- We are masters of abstraction and indirection. Programmers know that perhaps even more than other people; our world is almost all symbols. But all of us, programmers or not, use symbols every day of our lives. We also often use ritual, and rituals often involve symbols - Wikipedia even defines ritual as "a set of actions, performed mainly for their symbolic value..". -

- Transfer pictures from bluetooth phones, difficulties and solutions. Like so many Mac operations, getting pictures from a Bluetooth phone to your Mac is actually very simple once you have done it once. If you've never done it, you may not have a clue where to start, and your phone's manual probably sends you off to get some piece of Windows software that won't help you at all. That's OK: everything you need is already built into your Mac. -

- ipconfig on Mac is not like the Windows command of the same name, but is still very useful. If you momentarily forget where you are at a Mac OS X terminal session, you might type "ipconfig /all" or something equally Windowish. You will get a response: -

- 'chown -R' is smarter than you think. I had email this morning from someone using "chown" to fix up permissions on a directory. He had discovered "-R" in the man page but had run into a small problem... That succesfully changed the ownership of the "dot" files, but had an unexpected (to him) side effect: /usr was also changed. -

- Writing and compiling c programs on Linux, common errors for beginners. Most Linux and Unix programs are written in C. When you download source for a project, it will often be C or C++ source code. You don't necessarily need to know a darn thing about C or anything else to compile the source if you aren't changing it. It may be helpful for you to understand a bit if you are having problems with the compile, but even that isn't really necessary. -

- No wonder people get confused. Lots of similar or related things, no end of licensing confusion, no end of general confusion. Let's try to cut through some of it. First, let's move back and look at the original Unix style multi-user model: dumb terminals, green screens (even if they were orange or white), the character based environment that all Windows folk loathe and disparage. How did that work? The application ran on the Unix server, and only sent characters back to the terminal, and the terminal only sent keystrokes to the Unix box. -

- Rebuild crashed Linux raid. Recently I had a hard drive fail. It was part of a Linux software RAID 1 (mirrored drives), so we lost no data, and just needed to replace hardware. However, the raid does requires rebuilding. A hardware array would usually automatically rebuild upon drive replacement, but this needed some help. -

- Sometimes when working with an image you want to make a certain color transparent. When working with a gif file this would make a round circle look round on any color background. This is actually very simple once you do it once. Finding the information for this took me a while so I thought I would pass it on to anyone that was interested. -

- Let's try to fix your lost root password the easy way first. The first thing to try is to boot to single user mode. This MIGHT not work for you, because your system might be configured to still ask for a root password to get to single user mode. If that's the case, we'll use another trick that replaces init with /bin/bash. -

- Perl has wonderful I/O capabilities. I'm only going to cover input here: reading from files or standard input. There are two ways to do that (actually a lot more than two, but this is supposed to be introductory material): you can open a specific file, or you can pass files on the command line and either open them individually or just ignore the whole thing and pretend everything is coming from STDIN. -

- Reviews of TightVNC and Chicken of the VNC. VNC is "Virtual Network Computing" and is a crossplatform method of allowing remote access to desktops (Windows or Unix/Linux, Mac and others)). It is conceptually like using Terminal Services or PcAnywhere etc for Windows but is license free and of course capable of serving Linux/Unix machines also. -

- Two Perl modules (Getopt and Getoptions::Long) work to extract program flags and arguments much like Getopt and Getopts do for shell programming. The Perl modules, especially GetOptions::Long, are much more powerful and flexible. -

- Before the wide spread availability of Perl, I would script ftp transfers with .netrc, ksh scripts and other clumsy ways. None of those methods are fun, flexible or easy. On the other hand, Perl's Net::FTP module is all of that. -

- Basic OS concepts. The CPU (Central Processing Unit) is the heart of any computer, but the operating system is the brain. Unfortunately, understanding exactly how these things really work can be difficult, because it's fairly hard to "play" with the operating system that you are actually using. You can do quite a bit with sophisticated debuggers, but eventually you run into confusion and difficulty. And, as you try more complex tasks, you run the risk of interfering with the real machine's operating system. Finally, modern CPU's are very complex, and that complexity can make it more difficult to understand basic concepts. -

- RedHat 7.3 and 8.0 do not have tools like Mandrakes urpmi for installing/updating rpms. After researching on Google groups for a similiar Redhat tool . APT seemed to be the best. I think its a tool from Debian linux. -

- Logical Volume Manager is now included with most Linux distributions. The RedHat 8.0 installer even allows you to create LVM volumes during initial install. LVM offers capabilities previously only found in expensive products like Veritas. If you plan on using LVM, I really recommend doing so on a RAID system, either hardware or software -

- Sending attachments from the command line with mutt, uuencode and other methods. If it's just arbitrary text or a file you want to send, and don't care about it looking like a real attachment, you can use ordinary "mail" ("mailx" on some Unixes) at the command line. However, that's NOT a mime attachment - it's just your file mixed in to the mail message. However, some mail clients will see it and treat it as a real attachment, so this may be "good enough": -